Control joints incomposite slab on metal deck /steel beam floor
Control joints incomposite slab on metal deck /steel beam floor
(OP)
I have a recently constructed composite slab on metal deck /steel beam floor system that the contractor has sawcut in 1 1/4" control joints. This comprimises the gravity capacity of the floor system.
Is there a method in which to treat the control joint to re-establish the contrete section or possibly a retrofit to the beams/stud confirguration to increase its capacity?
Is there a method in which to treat the control joint to re-establish the contrete section or possibly a retrofit to the beams/stud confirguration to increase its capacity?






RE: Control joints incomposite slab on metal deck /steel beam floor
RE: Control joints incomposite slab on metal deck /steel beam floor
one example is
http://www.lsepoxies.com/
but if you google concrete repair you will get heaps of suppliers.
Call them up and ask them to specify an appropriate product.
One note, if the sawcut is towards the ends of the slab span, then you may want to check that the decking can take the shear by itself rather than relying on the bond of the repair grout. Just a thought.
Regards
csd
RE: Control joints incomposite slab on metal deck /steel beam floor
RE: Control joints incomposite slab on metal deck /steel beam floor
What about the effect of the control joints relative to the composite beam design? Im concerned about the reduction in concrete section relative to stud count, beam deflection etc as the floor see its design live load?
RE: Control joints incomposite slab on metal deck /steel beam floor
RE: Control joints incomposite slab on metal deck /steel beam floor
Considering the composite beam action, I would have 2 main concerns:
1. as mentioned above if the joint is over the beams then it will induce cracking reducing the shear transfer of the stds.
2. if the joint is next to the beam, then it will reduce the effective width of slab that can be taken in composite action.
The repair mortars mentioned above do provide good bond to the concrete if used with the correct surface primers e.t.c, but personally I would prefer not to rely on it for structural stability.
Where one of the above 2 points applies, you may want to consider cutting grooves and installing 1' long rebar dowels for shear transfer as well as installing the grout.
regards
csd
RE: Control joints incomposite slab on metal deck /steel beam floor
RE: Control joints incomposite slab on metal deck /steel beam floor
RE: Control joints incomposite slab on metal deck /steel beam floor
A potential problem to consider is the fire rating of the slab system, as this is part of the primary gravity load system. Most epoxy turns to goo at low elevated temperature. I would research this fire rating issue with the architect and the building official.
Are the composite beams controlled by wet concrete dead load or composite dead and live loads? You might be able to "pencil whip" the beams to work with a smaller T-C lever arm and using the actual 28 day strength breaks.
Cover plating the beams that are overstressed is an ugly but proven method if things look too dire.